they fired r.p.g.s at us. once you start hearing the snaps of their rounds, that means they're right on you. >> logan: our cameraman, ray bribiesca, stayed close to the soldiers to capture the fight. >> hintz: we need a fire mission. >> logan: hintz ordered in mortars. ( explosions ) here you can see captain hintz on the hood of our truck, completely exposed to enemy fire. he's trying to secure the 200- pound tow bar so the convoy could get moving. >> hintz: get in the truck, get in the truck. start moving. >> logan: the convoy still had to fight its way though the ambush. after 30 minutes of constant fighting, it was over. hintz believes they killed 15 enemy fighters, with no american casualties. his soldiers were relieved, and captain hintz felt lucky to be alive. >> hintz: i had to jump on the hood to get the tow bar up, and so i'm on the hood and rounds are cracking everywhere. it was insane. >> logan: there are more than 12,000 soldiers at dozens of outposts along the border dealing with the same problem